Impact Significance: Risk Based Approach

Author: Rebecca Hewlett

Xodus Group

Presentation Outline

>Requirement for impact significance assessment

> Identifying the issues and recording the process

>Methods of determining impact significance

>Xodus perspective based on project experience

>An approach to significance assessment that incorporates impact

likelihood

>Common pitfalls to watch out for and a brief worked example

>Summary

Statutory requirements to establish impact significance

Environmental Impact Assessment to inform an Environmental Statementa description of the likely significant effects; anda description of the measures envisaged in order to avoid, reduce and, if possible remedy significant adverse effects on the environment.

Habitats Regulations and Appropriate AssessmentAny plan or project not directly connected with or necessary to the management of the site but likely to have a significant effect thereon, either individually or in combination with other plans or projects, shall be subject to appropriate assessment of its implications for the site plans or projects, shall be subject to appropriate assessment of its implications for the site in view of the site's conservation objectives.

Strategic Environmental AssessmentEnvironmental assessment is carried out on certain plans and programmes which are likely to have significant effects on the environment.

Environmental and Social Impact Assessment under the Equator PrincipalsProjects with potential significant adverse social or environmental impacts that are diverse, irreversible or unprecedented.

Impact Significance as a project tool

As well as the various public documents required to gain project consent and/or project funding establishing potential impact significance is an important project level tool which can assist the project team in:

> Early environmental impact risk assessment;> Site and concept selection;> Project design refinements;> Schedule/project non approval risk; and> Identification of appropriate and efficient mitigation strategies.> Identification of appropriate and efficient mitigation strategies.

For both statutory and internal project purposes the establishment of potential and residual impact significance needs to be clear, logical, auditable and consistently recorded.

When problems arise, it is often not that impact significance assessment is incorrect, rather its the process by which they have been determined has not been recorded and communicated logically and effectively.

Identifying the issues for significance assessment

The first step is to identify which issues should be included in the assessment (and justify why others have been excluded).

Since this process determines the scope of the impact assessment it is critical that it is recorded in a clear, defendable and transparent way.

Environmental Issues Identification ENVID Workshop

> Undertaken during scoping and revisited throughout the project as designs are refined and mitigation strategies developed.

> Undertaken during scoping and revisited throughout the project as designs are refined and mitigation strategies developed.

> Workshop includes relevant project staff including engineers, environmental, social (where appropriate) and methodically works through all project aspects and makes an assessment of each in terms of potential significant impact.

> Formal process that is facilitated and scribed where all issues are considered and included or excluded in an auditable way.

> Output is a matrix which records assessment of each impact significance in terms of its consequence and its likelihood. Example next slide

Example Aspect- Receptor Interactions Matrix from ENVID

Wat

er Q

ualit

y

Sea

bed

Impa

cts

Flor

a an

d Fa

una

Con

serv

atio

n

Air

Qua

lity

(loca

l)

Air

Qua

lity

(Reg

iona

l)

Ozo

ne D

eple

tion

Glo

bal w

arm

ing

Res

ourc

e an

d E

nerg

y U

se

Oth

er S

ea U

sers

Was

te

Lega

l com

plia

nce

Rep

utat

ion

Liab

ility

Process

Pla

nned

or

Unp

lann

ed

Activity Aspect

Receptor

Wat

er Q

ualit

y

Sea

bed

Impa

cts

Flor

a an

d Fa

una

Con

serv

atio

n

Air

Qua

lity

(loca

l)

Air

Qua

lity

(Reg

iona

l)

Ozo

ne D

eple

tion

Glo

bal w

arm

ing

Res

ourc

e an

d E

nerg

y U

se

Oth

er S

ea U

sers

Was

te

Lega

l com

plia

nce

Rep

utat

ion

Liab

ility

Riser and Mooring Installation Connection of risers to FPSO Chemical use and discharge P

Riser and Mooring Installation Connection of risers to FPSO Accidental spill of chemicals UP

Riser and Mooring Installation Presence of FPSO Installation Vessels. Vessel presence and interference with other sea users P

Riser and Mooring Installation FPSO Installation Vessels Oil and chemical spill risk - small operational spills UP

Riser and Mooring Installation FPSO Installation Vessels Oil and chemical spill risk - total loss of inventory UP

Riser and Mooring Installation Dropped objects Seabed impacts, interference with other users, oil spill risk

UP

Riser and Mooring Installation Operation of FPSO installation vessels Resource use and atmospheric emissions P

Riser and Mooring Installation Operation of FPSO installation vessels Noise emissions - disturbance to marine mammals P

Pla

nned

or

Unp

lann

ed

Determining Impact Significance –Consideration of Likelihood

There is a well established approach of using the receptor sensitivity and the impact magnitude to derive impact significance.

SNH 2009 handbook on environmental impact assessment:Expressing the significance of the impacts of the project, usually in relative terms, based on the principle that the more sensitive the resource, the more likely the changes and the greater the magnitude of the changes, compared with the do nothing comparison, the greater will be the significance of the impact.

SNH make the point that the more likely the change the greater the significance will be.

For the purposes of this presentation I will use the following definition:receptor sensitivity X potential impact magnitude =

potential environmental consequence

The likelihood of the potential overall consequence of the impact occurring is then explicitly taken into account to derive the impact significance.

Xodus Project Perspective – Oil and Gas and Marine Renewables

Oil and Gas and associated infrastructure offshore, near shore and onshore

Offshore Wind, Wave and Tidal Energy

Impact Significance and Likelihood :The Communication Challenge

Q: How to effectively and transparently communicate an impact significance that incorporates an assessment of likelihood?

Examples: oil spill, bird strike, seal injury etc.

For some projects consequences can be very severe BUT also have low probability/frequency.

A simple assumption that all impacts identified are bound to happen does not usefully inform the impact assessment in these cases.

Here impact significance assessment is often supported by modelling and this can be explicitly included in significance assessment (see next slide).

NB: This is where significance of impact and significance of risk start to be used interchangeably in some industries.

Example of Probability/Frequency GuidelinesFrequency / Probability Category

Routine (Planned) Operation Frequency Accidental Event (Probability)

5 Continuous emission or permanent change over more than 5 years

Likely

10-1 >1 per year

Event likely to occur more than once on the facility.

4 Continuous emission or permanent change over less than 5 years

OR

Regular over more than 3 years

Possible

10-2 – 10-1 per year

Could occur within the lifetime of the development.

3 Regular over less than 3 years

OR

Intermittent over more than 3 years

Unlikely

10-3 – 10-2 per year

Event could occur within the life of 10 similar faculties, Has occurred at similar facilities.

2 One off event over lifetime of development over several weeks durations

OR

Once per year for <24 hours

Remote

10-5 – 10-3 per year

Similar even has occurred somewhere in industry or similar industry but not likely to occur with current practices and procedures.

1 One off event over lifetime of development for < 5 days

Extremely remote

<10-5 per year

Has never occurred within industry or similar industry, but theoretically possibly.

Determining Impact Significance including regulatory, stakeholder and likelihood considerations

As already outlined:receptor sensitivity X potential impact magnitude =

potential environmental consequence

Where appropriate two other factors: stakeholder perception and regulatory compliance are then combined with environmental consequence to give an overall consequence.overall consequence.

The potential overall consequence is then combined with likelihood to give the impact significance.

The inclusion of regulatory, stakeholder and likelihood considerations provides an integrated assessment of the significance of risk/impact.

Flowchart on next slide

Impact Significance flow chart

Significance RankingLikelihood

5 4 3 2 1 0

Consequence Regulatory Environment Stakeholder Continuous / likely

Regular / Possible

Intermittent / Unlikely

One off Event / Remote

One off Event / Extremely Remote

Will not occur

5 Severe Activity prohibited Likely major breach in compliance resulting in prosecution

Severe magnitude / sensitivity ranking

International concerns

25 20 15 10 5 0

4 Major Possibly major non-compliance

Major magnitude / sensitivity ranking

National concerns

20 16 12 8 4 0

ranking

3 Moderate Possibly non-compliance

Moderate magnitude / sensitivity ranking

Regional concerns

15 12 9 6 3 0

2 Minor Regulatory terms or corporate policy set defined conditions

Minor magnitude / sensitivity ranking

Local concerns

10 8 6 4 2 0

1 Negligible No specific statutory control

Negligible magnitude / sensitivity ranking

Individual concerns

5 4 3 2 1 0

0 Positive Impact

N/a Positive benefit or enhancement

No public interest or improves aspect of community importance

0 0 0 0 0 0

Some challenges in significance assessment

When integrating impact consequence and likelihood we can sometimes trip up by double counting impacts through confusion around impact magnitude, impact consequence and likelihood. Example next slide

Definition consistency across different disciplines – especially matching up quantitative issues such as compliance with noise emissions legislation and something more qualitative such as an assessment of habitat fragmentation.something more qualitative such as an assessment of habitat fragmentation.This is a particular issue when using specialist sub consultants who may not be familiar with the approach. Good communication and worked examples key here.

Consistency across different environments, and assessment regimes.E.g. large projects that include onshore/offshore components in one ES. Require very clear and explicit boundary setting and potentially varying definitions and assessment methods for some components.

Example of Double Counting leading to under estimate of significanceUnder estimate of impact significance:

> Impact Magnitude assessed as negligible forfatal seal-tidal turbine interaction as this impact is considered extremely unlikely.

> Overall consequence assessed as lowbecause negligible magnitude has brought down the high receptor sensitivity, regulatory and stakeholder ratings.

> Impact significance assessed as negligible as the low overall consequence is combined with the negligible likelihood.the negligible likelihood.

More accurate assessment:> Impact magnitude assessed as severe as the

assumption is made that the impact will occur.> Overall consequence is high as receptor

sensitivity is high and there are also high ratings for stakeholder and regulatory requirements.

> Impact significance is moderate (i.e. requiring mitigation) as the very low/negligible likelihood of the impact is combined with the high consequence.

Summary

Assessment of significance is key to many aspects of the work we do as environmental practitioners.

The main requirement with regards to significance assessment is that the process is clear and unambiguous and recorded.

ENVID workshops facilitate and record issues identification in a transparent way.way.

Using a method of assessing impact significance that explicitly takes account environmental, stakeholder and regulatory potential consequence and then combines this overall consequence with likelihood to give the impact significance teases apart the various aspects of significance assessment.

The strength of this explicit method is that each step deals with one aspect of significance at a time and, when used correctly, allows stakeholders to follow the logical steps that have lead to the impact significance rating.